Tool for removing covering material from an electrically conductive cable

ABSTRACT

A HAND TOOL FOR REMOVING INSULATION AND/OR SEMICONDUCTIVE MATERIAL FROM AN ELECTRICALLY CONDUCTIVE CABLE. THE TOOL INCLUDES A CYLINDRICAL BODY THROUGH WHICH A CABLE MAY BE MOVED ENDWISE AND A BLADE FIXED TO THE BODY AND HAVING TWO CUTTING EDGES POSITIONED IN PLANES PARALLEL   TO AND TRANSVERSE TO THE CENTERLINE OF THE CABLE RESPECTIVELY.

ov. 16, 1971 R. G. HORROCKS 3,620,M&

TOOL FOR REMOVING COVERING MATERIAL FROM AN ELECTRICALLY CONDUCTIVE CABLE Filed Nov. 19, 1969 2 Shoots-Shoot 1 Nov. 16, 197] R. G. HORROCKS 3,620fifl4 TOOL FOR REMOVING COVERING MATERIAL FROM AN ELECTRICAL-LY CONDUCTIVE CABLE Filed Nov. 19, 1969 2 Sheets-Sheet 2 w INVENTOR.

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United States Patent Ofice US. Cl. 81-9.5 C Claims ABSTRACT OF THE DISCLOSURE A hand tool for removing insulation and/ or semiconductive material from an electrically conductive cable. The tool includes a cylindrical body through which a cable may be moved endwise and a blade fixed to the body and having two cutting edges positioned in planes parallel to and transverse to the centerline of the cable respec- This application is a continuation-in-part of my copending application Ser. No. 846,196, filed July 30, 1969, and now abandoned.

BACKGROUND The prior art which is most nearly pertinent to this invention and known to me are my Pat. No. 3,377,891 and my application Ser. No. 710,012 filed Mar. 4, 1968, and now Pat. No. 3,548,690, and Matthews Pat. No. 3,398,610.

The tools of my Pat. No. 3,377,891 and my application Ser. No. 710,012 are suitable for removing cable covering material so as to form a square end surface on such material. However, neither of these tools is entirely satisfactory with cables in which the conductor is not symmetrically mounted within the covering material. It is imperative that the cutting blade should not engage and nick the conductor and, accordingly, it has been necessary to position the cutting edge of the blade just out of contact with the conductor where the covering material is thinnest. However, when so positioned the blade does not sever all the covering material where it is thicker with the result that the spiral chip which is formed is not fully severed and may foul the tool.

The tool of Matthews Pat. No. 3,398,610 was aimed at a solution of this problem but comprises a number of unnecessary parts and includes means for mounting the cutting blade which permits the blade to vary its position in use.

The present invention insures the complete severing of the chip regardless of the variations in thickness of the covering material in offset positioning of the conductor therein when forming a square end cut and includes a minimum number of parts and means for fixedly securing the blade to the tool against any variation of position in use.

SUMMARY OF THE INVENTION A tool embodying this invention includes an elongated cylindrical body having a passage or a bore of such a diameter as to have a close sliding fit with the surface of a cable from which covering material is to be removed. A blade is securely fixed in position on the body and against variation in position in use. The blade has two cutting edges of unequal length and with a common end, disposed at a wide included angle, for example, an angle of between about 70 and about 90 to one another, the first edge being positioned in a plane transverse to the centerline of the bore and the second edge being posi- 3,620,104 Patented Nov. 16, 1971 tioned in a plane substantially parallel to the centerline of the bore.

By suitably positioning the first cutting edge of the blade relative to the cable, one or more layers of the covering material may be removed from the conductor. The outer semiconducting material, that material and the insulation, and that material, the insulation and the inner semi-conducting material may be removed when the blade is positioned with the first cutting edge substantially tangent to the outer circumference of the insulation, or of the inner semi-conducting material or of the conductor, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a tool embodying the present invention for removing the outer layer of semiconductive material from an electrically conductive cable;

FIG. 2 is a transverse, sectional view, taken on line 22 of FIG. 1;

FIG. 3 is a longitudinal, sectional view, taken on line 3-3 of FIG. 1;

FIGS. 4 and 5 are, respectively, perspective views of a cable preliminary to, and after, removal of the outer layer of semi-conductive material therefrom by the tool of FIGS. 1 to 3;

' FIG. 6 is a perspective view of the blade attached to the tool as shown in FIGS. 1 to 3;

FIG. 7 is a sectional view similar to FIG. 2 but showing an adjustable carrier for the cutting blade;

FIG. 8 is a side elevational view of the blade carrier of FIG. 7;

FIG. 9 is a perspective view of another tool embodying the present invention and adapted to remove one, two or three layers of material covering the conductor of an electrical cable;

FIG. 10 is an end view of the tool of FIG. 9;

FIG. 11 is a longitudinal, sectional view of the tool of FIG. 9 taken on line 1111 of FIG. 9;

FIG. 12 is a perspective view of the cable of FIG. 9 from which insulation and the outer and inner layers of semi-conductive material have been removed by the tool of FIG. 9;

FIG. 13 is a perspective view of the cutting blade of FIGS. 9 to 11;

FIG. 14 is a perspective view of a modified form of cutting blade embodying the present invention; and

FIG. 15 is a view similar to FIGS. 13 and 14 but showing another modified form of cutting blade.

The tool shown in FIGS. 1 to 6 is particularly adapted for removing the outer layer of semi-conductive material from insulation surrounding the conductor of an electrically conductive cable. In these figures, 1 designates an elongated conductive body which is fitted with aligned bushings 3 and 5 retained in position by screws 7 which project into annular grooves 9 in the outer surface of the bushings. A passage or bore 13 extends through the bushings and body. The portion of the passage 13 in bushing 3 has close fitting engagement with the outer surface of an electrical cable, such as 15 in FIGS. 4 and 5, from which the outer semi-conducting material 17 is to be removed. The portion 14 of the passage 13 in body 1 and the portion 16 in bushing 5 are only slightly larger in diameter than the insulation 21 of the cable 15. The bushing 5 may be omitted, if desired, when the portion 14 of the passage 13 fits so closely around the insulation that the cable cannot move laterally far enough for the blade to gouge the insulation.

The body 1 is cut away transversely to provide a recess 23 which extends across and intersects with the passage 13. As shown recess 23 makes an angle of about 5 with 3 the longitudinal centerline of the portion of the passage 13 in the body 1. A cutting tool 25 is positioned in recess 23 and is firmly secured in place against movement in use, as by a screw 27 which extends through slot 29 in the blade and has screw threaded engagement in the body.

The blade 25 is provided with a first cutting edge 31 and a second cutting edge 33. These two edges are disposed at a wide included angle to one another and when the blade is positioned in the body, as in FIGS. 1-3, the longer cutting edge 31 will lie on a plane substantially parallel to the centerline of the passage 13 and of the cable positioned in bushing 3 while the shorter cutting edge 33 will lie in a plane transverse to that centerline.

The blade 25 has a plane bottom surface 35 which rests on the body, as shown in FIG. 2, and is cut away from the longer edge 31 to form an upwardly extending inclined surface 37 which makes a small angle, for example, from about 25 to about 35 with the bottom surface 35 of the blade. The blade 25 is also cut away to form a surface 39 which makes a small angle, for example, between about 25 and about 35 with the adjacent side of the blade. Thus the blade, as is shown in FIG. 6, has long and short cutting edges 31 and 33 which make a wide included substantially right angle with one another and have a common end. The sloping surfaces 37 and 39 serve to direct away from the cutting edges material severed by the latter from a cable.

It will be understood that when it is desired to remove the outer layer 17 of semi-conductive material from an electrically conductive cable, such as that shown at 15 in FIG. 4, the blade 25 will be positioned with its cutting edge 31 substantially tangent to the circle defining the inner surface of the outer layer of semi-conductive material 17, i.e., between that layer and the layer of insulation 21 which surrounds the inner layer 41 of semi-conductive material immediately enclosing the conductor 43. When a cable having a close sliding fit in the passage or bore 13 of bushing 3 is inserted in that bore and the tool is rotated to advance the cutting edge 31 against the material and is moved axially relative to the cable, that edge will sever the outer layer of semi-conductive material 17 from the insulation 21 and the cutting edge 33 will sever that layer transversely and the resulting endless chip will move along surfaces 37 and 39 and thence out of the body 1.

It will be noted that the recess 23 in which blade 25 is mounted is of substantial width. Recess 23 should be wide enough to insure free passage of the chip out of the tool. For a cable of about 1 in diameter, a suitable width of blade 25 is about /2". As the cable diameters increase, the blade width should increase. For a cable of about 2" in diameter, a suitable width of blade 25 would be about A". As stated above, the recess 23 of FIG. 1 makes an angle of about with the longitudinal centerline of the passage 13. That angularity is suitable for cables of the smaller diameters, for example, about 1" but should decrease as the cable diameter increases, i.e., to about 0 with cable diameters of about 2 /2. Since the effort to remove the material increases with the width of the chip, the angularity of the recess should decrease as the diameter of the cable increases to keep the required effort in a small range. It is to be understood that, when desired, the recess 23 may be substantially at a right angle to the longitudinal centerline of the passage 13.

In the modification shown in FIGS. 7 and 8, the blade 25 is secured, as by screw 46, to a carrier 47 which may be secured to body 1 in adjusted positions by a screw 49 extending through elongated hole 48 and into the body to locate the cutting edge 31 tangent to the inner circumference of the material to be removed from cables of a small range of diameters.

The cutting blade 65 shown in FIGS. 9 to 13, inclusive, may be used to remove the outer layer of semi-conductive material but is particularly adapted to removal of the outer layer of semi-conductive material and the layer of insulation, or both layers with the inner layer of semiconductive material without nicking the conductor. The tool of FIGS. 9 to 13 includes an elongated cylindrical body 51 fitted with a bushing 53 which has a passage or bore 55 only slightly greater than the outside diameter of the cable from which material is to be removed so that the cable has a close sliding fit in the bushing. The bushing is held securely in fixed position in the body by any suitable means, for example, a screw 57 which has threaded engagement in the body and projects into an annular recess 59 in the bushing. At oneend of body 51 is positioned a blade 65 which is held in place on the body by screw 67 which extends through slot 69 in the blade.

The blade 65 is provided with a plane lower surface 71 which seats in a recess 72 in the end of body 51 and is inclined at a small angle, for example, between about 2 and about 5 to the longitudinal centerline of the bore in bushing 53. The blade has a long cutting edge 73 and a short cutting edge 75 which edges make a wide, included, substantially right angle with one another and have a common end. The surface of the blade slopes upwardly from the lower surface 71 as at 77, and slopes transversely from the adjacent side surface of the blade, as at 79. The surfaces 77 and 79 make angles of between about 25 and about 35 with the bottom and side surfaces of the blade.

When only the outer layer of semi-conductive material 83 is to be removed from a cable, such as 81 of FIG. 9, the blade 65 is positioned with its bottom surface 71 in contact with the sloping surface of recess 72 of the tool and with the short cutting edge 75 positioned parallel to the longitudinal centerline of the bore in bushing 53 and substantially tangent to the inner surface of the outer layer of semi-conductive material and with the longer edge 73 positioned transversely to that centerline. The cable is then inserted in the bore 55 of bushing 53 and the tool and cable are moved relatively rotationally against the cutting edges 73 and 75 and longitudinally with the result that the outer layer of semi-conductive material 83 is cut transversely through and severed from the layer of insulation 85 and the resulting ribbon or chip of material moves along surfaces 77 and 79 and thence away from the tool.

When both the outer layer of semi-conductive material and the layer of insulation are to be removed, the blade is adjusted to position edge 75 of the blade tangent to the inner surface of the insulation. When it is desired to remove the inner layer of semi-conductive material 86 (FIG. 12) as well as the other two layers, the blade is positioned with cutting edge 75 tangent to a circle enclosing the conductor 89.

It will be understood that the tool of either the modification of FIGS. 1 to 8 oro that of FIGS. 9 to 12 may be used with cables which differ in diameter but since it is important that in each instance the cable should have a close sliding fit in the tool and that the cutting edges should be positioned with exactness, the range of sizes of fication of FIGS. 1 to 8 or that of FIGS. 9 to 12 may be cable from which material may be removed with any given tool is quite limited. By providing bushings with bores ranging from about /2" to about 1%" in diameter, and mounting the tool adjustably on the body in any suitable manner, for example, as shown in FIGS. 7 and 8, the outer layer of semi-conductive material and insulation may be removed from cables ranging in diameter from about /2" to about 1 /8".

Since there are cables larger than 1 /2" and it is preferable, economically, to restrict the costs of the blade holders of the tools, two or more additional sizes of holders may be used. For example, one holder would take cables ranging from about A" to about 1 /2" and another holder would take cables ranging from about 1" to 1%". Of course, these ranges may be varied as desired.

FIG. 14 shows a modified form of cutting blade 90 which is preferable in certain respects to blade 25 of FIG. 6 and blade 65 of FIG. 13. Cutting blade 90 consists of a flat, thin body portion 91 and a flat thin flange portion 92 at one of the body portion 91. One edge of body portion 91 is beveled as at 93 and forms a cutting edge 95 at the intersection of that surface with the flat undersurface 97 of body portion 91. Flange portion 92 has an outer surface 98 and a beveled surface 99 corresponding to the beveled surface 93 and forming a cutting edge 101 at the intersection of the beveled surface 99 with surface 98. At the other end of portion 91 a notch 106 is formed for a securing bolt. It will be noted that the long and short cutting edges 95 and 101 make a wide included substantially right angle with one another and have a common end point indicated at 105.

The cutting blade shown in FIG. 15 resembles the blades of FIGS. 13 and 14 but differs from each one in certain respects. The blade 110 of FIG. 15 includes a flat thin body portion 112 and a thin flange 114 at one end thereof. The body portion is beveled along one edge as at 116, making an angle of between about 25 and about 35 with the bottom surface of body 110. The end of flange 114 is similarly beveled as at 118. The inner surface 120 of flange 114 makes an included angle of about 90 with the top surface of body 110. The outer surface of flange 114 is inclined at an angle to surface 120. The edge 122 on body 110 and edge 124 on flange 114 have a common end and make a wide included angle, for example, from about 70 to about 85. Notch 126 serves to receive a securing bolt such as bolt 67 of FIG. 11.

It will be understood that cutting blades 90 or 110 may be used in lieu of blades 25 or 65 as desired.

It will be understood that the shorter cutting edges of blades 25, 65, 90 and 110 should be at least as long as the longitudinal thickness of the chip or ribbon of covering material being removed from the cable; and that the longer cutting edges of those blades should be at least as long as the radial or transverse thickness of the material being removed. Accordingly, the longer cutting edge will be at least twice and usually several times as long as the shorter cutting edge.

Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated or carrying out this invention, I state that the subject matter which I regard as being my invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above specifically described embodiments of the invention may be made without departing from the scope of the invention as set forth in what is claimed.

What is claimed is:

1. A hand tool for removing covering material from an electrically conductive cable which comprises an elongated cylindrical body having a longitudinal passage whose inlet end is only slightly larger in diameter than that of the cable from which covering material is to be removed so that the cable will have a close sliding fit in that end of the passage, and a blade fixedly secured to the tool against variation of position in use and having two cutting edges of different lengths with one edge being disposed in a plane transverse to the centerline of the passage and with the other cutting edge disposed in a plane substantially parallel to the centerline of the passage and substantially tangent to the inner circumference of the material to be removed.

2. The tool set forth in claim 1 in which a bushing in the body forms the inlet end of said passage.

3. The tool set forth in claim 1 in which an opening in the body beyond the blade forms a part of said passage and has a diameter only slightly larger than that of the cable after the removal of covering material therefrom by said cutting blade.

4. The tool set forth in claim 1 in which a bushing in the body forms the outlet end of said passage.

5. The tool set forth in claim 4 in which the bushing forming the outlet end of said passage has an internal diameter only slightly larger than that of the cable after removal of the covering material therefrom by the cutting blade.

6. The tool set forth in claim 1 in which the longer cutting edge of the blade is disposed in a plane at substantially right angles to the centerline of said passage.

7. The tool set forth in claim 1 in which the longer cutting edge of the blade is disposed in a plane substan tially parallel to the centerline of said passage.

8. The tool set forth in claim 1 in which the cutting edge of the blade which is substantially parallel to the centerline of the cable is positioned substantially tangent to a circle defining the outermost surface of the conductor of the cable.

9. The tool set forth in claim 1 in which the blade is fixedly mounted on a carrier and the carrier is adjustably attached to the body to position one cutting edge substantially tangent to the inner surface of the layer of covering material to be removed from a cable.

10. The tool set forth in claim 1 in which the blade consists of a flat thin body having a plane bottom surface and a thin flange at one end thereof having a plane outer side surface, the blade being beveled at angles of about 25 to about 35 with said bottom and side surfaces and forming a long cutting edge on the body and a short cutting edge on the flange.

References Cited UNITED STATES PATENTS 4/1968 Horrocks 81-95 C 8/1968 Matthews 81-95 C US. Cl. X.R. 30-901; -31 

